Crows Solve Visual Tasks Twice as Fast as Monkeys

Carrion crows make visual decisions twice as fast as monkeys, according to a new study released this week.

The research team tested two hand-raised carrion crows on a task typically used to study primate decision-making. The birds sat in front of a touch-sensitive monitor that displayed a cloud of white dots against a black background. A subset of these dots drifted in a specific direction, and the crows had to identify that direction by pecking one of the targets next to the screen. The researchers rewarded correct answers with a mealworm.

This type of experiment is known as the random-dot-motion task. In primate studies, it has shown that neurons in the neocortex accumulate visual evidence over time. Their firing rates rise until they cross a threshold, prompting the animal to commit to a choice. Birds do not have a neocortex, which raised questions about how their brains handle similar cognitive loads. Andreas Nieder, a neurobiologist at the University of Tübingen, noted that the specific mechanism for avian decision-making was a major open question.

Nieder and colleague Philipp Schmidbauer recorded the birds' brain activity while they performed the task. They deliberately kept the setup identical to the monkey version to ensure a direct comparison. The only physical difference was that the crows used a peck to indicate their choice, while monkeys typically use an eye movement. The researchers varied the difficulty of the task by adjusting the percentage of dots moving coherently. The easiest condition involved 81 percent of dots moving in unison, while the hardest involved only 3 percent. They also included a condition with zero percent coherent motion, where no correct answer existed.

The crows solved the task using the same mathematical logic as primates, despite their different brain structures. They reached their decisions in half the time required by monkeys. The findings suggest that a brain without a neocortex can still arrive at decisions through a comparable process.

The study confirms that the rapid processing speed of crows does not rely on the same neural architecture as primates. The data shows that different brain organizations can produce similar decision outcomes. The crows' ability to match primate logic at a faster rate provides new insight into the flexibility of neural decision-making systems.